Shameless green varied winning positions

tic-tac-toe/tic_tac_toe.rb

@@ -28,6 +28,12 @@ def winning_move?(square, player)
   def winner
     first_position_in_rows = [0, 3, 6]
     first_position_in_rows.each { |position|  return mark_at(position) if winning_row(position) }
+    first_position_in_columns = [0, 1, 2]
+    first_position_in_columns.each { |position| return mark_at(position) if winning_column(position) }
+    first_position_in_left_diagonal = 0
+    return mark_at(first_position_in_left_diagonal) if winning_left_diagonal(first_position_in_left_diagonal)
+    first_position_in_right_diagonal = 2
+    return mark_at(first_position_in_right_diagonal) if winning_right_diagonal(first_position_in_right_diagonal)
     return '-'
   end
 
@@ -37,6 +43,24 @@ def winning_row(position)
     mark_at(position.next) == mark_at(position.next.next)
   end
 
+  def winning_column(position)
+    position_occupied?(position) &&
+    mark_at(position) == mark_at(position + 3) &&
+    mark_at(position + 3) == mark_at(position + 6)
+  end
+
+  def winning_left_diagonal(position)
+    position_occupied?(position) &&
+    mark_at(position) == mark_at(position + 4) &&
+    mark_at(position + 4) == mark_at(position + 8)
+  end
+
+  def winning_right_diagonal(position)
+    position_occupied?(position) &&
+    mark_at(position) == mark_at(position + 2) &&
+    mark_at(position + 4) == mark_at(position + 4)
+  end
+
   def position_unoccupied?(position)
     mark_at(position) == '-'
   end

tic-tac-toe/tic_tac_toe_test.rb

@@ -1,5 +1,5 @@
 require 'test/unit'
-require './tic_tac_toe'
+require_relative './tic_tac_toe'
 
 class GameTest < Test::Unit::TestCase